A Bait Casting Machine (BCM) is a hydraulically operated device designed to deploy baited hooks during pelagic longline setting (prior to the development of BCMs, individual hooks were cast by hand). BCMs are commonly used in high seas pelagic fisheries and are an integral part of the line setting process. The original BCM (developed by Gyrocast Pty Ltd) improved fishing efficiency and, if used correctly, had the potential to reduce the risk of seabird bycatch. Gyrocast BCMs had a five second cycling time, variable power control, the ability to cast hooks up to 23 metres, directional control (i.e. able to switch between port and starboard) and a gimballed mount to compensate for vessel movement (Brothers et al., 1999). These features help to reduce bait loss to birds and seabird bycatch by allowing fishermen to "place" baited hooks under the protection of a streamer line, even in strong winds.

Trials of the early BCMs (Gyrocast), indicated that these machines substantially reduced bait loss to seabirds provided bait was consistently landed beneath streamer lines (Brothers et al., 1999). Later models of BCMs have not incorporated the key features necessary to reduce seabird bycatch, in particular distance control. Currently, there is inadequate data to quantify the effectiveness of the current version of these machines.

Recommendations for deployment

The original Gyrocast machine showed great promise as an aid to reducing seabird bycatch. However, these devices are no longer in production. Current models of BCM are designed to improve fishing efficiency and should not be regarded as seabird bycatch mitigation measures.

Problems and solutions

The BCMs currently used lack control over casting power. Consequently, the arc of the cast can interfere with streamer lines and bait may be landed well beyond the location of the streamer line. The ability to adjust the distance and direction of cast are critical performance features of BCMs and should be built into future machines if they are to be regarded as contributing to the reduction of seabird bycatch.

Combinations of measures

If used to improve fishing efficiency, bait casters should be used with a suite of mitigation measures, including:

- Streamer lines

- Line weighting.

Ease of Deployment and Safety

The BCMs currently used lack control over casting power. Consequently, the arc of the cast can interfere with streamer lines and bait may be landed well beyond the location of the streamer line. The ability to adjust the distance and direction of cast are critical performance features of BCMs and need to be built into future machines if they are to be regarded as contributing to the reduction of seabird bycatch.

Further Research

No further research is considered necessary at this stage. The critical next step is to manufacture BCMs with variable power control and to ensure they are operated in such a way that baited hooks are consistently placed beneath the area of the water protected by the streamer line(s).